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ValidationJune 16, 2026By Maarten Follaets

Welcome to the Ventropolis blog

Let me start with the thing I learned the hard way.

Most startups do not fail because the team could not build the product. They fail because they built something nobody wanted to pay for. The building was never the hard part. Knowing what to build is.

So that is what I am writing about here.

Why I am writing this

At Ventropolis we run structured validation loops with founders. We take your riskiest assumptions and turn them into real evidence, fast. And we keep seeing the same traps, plus the same handful of moves that get people unstuck.

I would rather put those in the open than bury them in a pitch deck. So expect posts on:

  • how to find the one assumption that sinks you if it is wrong
  • designing tests small enough to run this week
  • reading the evidence honestly, even when it stings
  • stories from real validation loops, anonymized

Build what customers will actually pay for. Everything else is a hobby.

What to expect

Short, practical, opinionated. No growth-hacking listicles. Just the validation craft we use every day. Want to go deeper? See how the loop works.

Glad you are here. Now go talk to a customer.

Frequently asked questions

What is a validation loop?
A structured cycle where you turn one risky assumption into real evidence: you frame the assumption, design the smallest test that could disprove it, run it with real customers, and decide. We run the loop with you, 2 to 4 times faster than figuring it out alone.
Do I need a finished product to start?
No. Most assumptions worth testing can be validated before you build, with conversations, landing pages, or concierge tests. The whole point is to learn what is worth building first.
What do I walk away with?
A Proof Board: a clear record of what you assumed, what you tested, and what the evidence actually showed. It is yours to keep and to show investors, teammates, or customers.

Put your assumptions to the test.

Foxy, your AI co-founder

Join early access and walk away with a plan, real evidence, and an honest verdict.